A Guilty Spark
One of my personal favorite archetypes, Watts have been around since their debut in The Shining Darkness in 2010. Their Thunder typing has helped them to synergize with cards like Thunder Sea Horse, and the "hunder" monsters in the past. Moving into the November 2019 format, a small Watt engine works well in a deck like Thunder Dragons. Monsters like Wattcobra and Wattgiraffe can be used as extenders by normal summoning them if you don't have access to Batteryman Solar. This can help you get into Some Summer Summoner more often.
The Watt monsters can also assist in setting up your endboard with a Thunder Dragon Colossus and/or Thunder Dragon Titan. After activating the effect of a Thunder Dragon monster in your hand, you can Tribute your summoned Watt for Colossus. Another option could be banishing a Watt monster in your hand and a Colossus on the field for Titan. As you can see, running a Watt engine in Thunder Dragon decks can prove useful in allowing your regular combos to be more consistent.
New support was recently released in Chaos Impact, in the form of Wattrain. This card is a searcher for Watts and also has a similar Graveyard effect to Thunder Dragon Fusion. Both cards can be banished from the GY during your Main Phase to help their respective archetypes. This means that a card like Foolish Burial Goods would be a good choice in a deck that runs both targets.
Wattrain can also search Wattcine, granting you Life Points each time one of your Thunder monsters inflicts battle damage. With Colossus and Titan having high ATK values, this card can replenish your LP while draining your opponent's. Regarding current time rules, Wattcine ensures that you will always remain ahead in LP if you can't swing for game.
Being able to get Watt monsters on the field with different names without using your Normal Summon is valuable. One card that can take advantage of this that is already being played in Thunder Dragons is Black Luster Soldier - Soldier of Chaos. It requires three monsters with different names and gains protection effects if a Level 7+ monster is used as material. A Colossus or Titan would be perfect for this, as Thunder Dragon combos should always have either of them out.
Outside of their use as an engine in other decks, a pure Watt variant could have potential because of the range of disruption effects available. However, these monsters can be slow since they want to be destroyed to activate their effects. On the other hand, resolving the effect of a destroyed Wattlemur can stop your opponent's next Battle Phase. This can easily give you the advantage with the use of heavy beatstick monsters, such as Wattaildragon, to boost the power of the pure Watt deck.
A popular Watt strategy that could make a resurgence is "Hopper Lock." This involves setting up at least two Watthopper monsters so that none of your Watt monsters can be targeted. With cards like Wattdragonfly and Wattrain, this has become easier than before. An effective lockdown of your monsters gives you the chance to exploit the battle effects of the weaker Watts. Although this lockdown is exposed to non-targeting destruction or removal effects that are being played at the moment. A simple way to counter this drawback is by running the "Solemn Brigade." While LP costs would sometimes result in a loss when time is called, cards like Solemn Judgment would not be risky to play if paired with Wattcine. This enables a less focused effort on managing your resources.
Overall, I believe Watts could be used to great effect, either alone or as an engine for Thunder Dragons. It allows for enhanced consistency while helping to control the board in a variety of ways. While the more renowned strategies may not have aged well, Watt monsters haven't lost their sting. With this in mind, I encourage you to take another look at what Watts can offer. The results may shock you.